The UK government is considering legislation to ban people from the net if they are found guilty of online copyright theft is a dramatic escalation in the battle against "piracy". Because there are about six million people a year that is estimated to download files illegally from internet. Music and film companies say that the illegal downloads cost them millions of pounds in lost revenues.

If the law were enacted it would turn ISPs, like BT, Tiscali and Virgin, into a pro-active police force who would have to monitor traffic on the internet in order to look out for copyright files being swapped online. So that, the internet service provider had force to take action over the users who access private material via their accounts.

This legislation would mean the UK would have the most stringent and prohibitive anti-piracy laws in the world.

It would be a technical challenge for ISPs to do this. Monitoring traffic that is shared using file-sharing tools like BitTorrent is perfectly feasible, as the programs use specific internet ports. In fact, ISPs already monitor file-sharing traffic across the net in order to shape the flow of information - prioritising certain bits of data over others.

Knowing where to look isn't the problem; knowing what to look for is. Every day many terabytes of data are being shared over the internet using file-sharing tools. Individual packets of information can be inspected. Would all digital content have to be watermarked? Would ISPs have responsibility for this? If not, who would?

And there is evidence that more people are encrypting files that they send over peer to peer networks, making it difficult to know exactly what they are sharing. That may give rise to further suspicion but will ISPs be given powers to force users to decrypt their files?

Internet service providers have long been loath to become the net police - for obvious legal and financial reasons. They see themselves as passive conduits, like a road network or the postal system.

The global record industry has been quick to back the government's proposal.
Digital rights activist will be outraged by this move. Monitoring our internet traffic will have huge privacy issues.

No-one can deny that the scale of copyright theft is mammoth. A cursory glance at a website like The Pirate Bay revels thousands of films, TV programmers, albums, software programs etc being shared across the net.

But there is legitimate debate about what this means to the global content industry and to consumers. Does it signal a seismic shift in the way people want to pay, use and share their content, and what we understand by copyright? Or is it wholesale theft that needs to be stamped out user by user by user?